GABRB1 and atypical Rett syndrome: Other GABA receptor genes including GABRA1, GABRB1, and GABRB3 have been associated with severe epilepsy phenotypes.41 While we did not find a sequence variant associated with epilepsy in this subject, the translocation likely disrupts patterns of X-inactivation and alters transcription patterns.42 Furthermore, MECP2 is associated with Rett syndrome and is approximately 2 Mb from the translocation breakpoint.